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United States Patent |
5,698,020
|
Salz
,   et al.
|
December 16, 1997
|
Photochromic dental material
Abstract
The invention relates to dental materials which contain a photochromic
material such as for example a photochromic dye, a photochromic glass, a
photochromic ceramic and/or a photochromic glass ceramic and which can be
visually distinguished from natural tooth material after irradiating with
light, but which assume their original colour again after a certain period
has expired.
Inventors:
|
Salz; Ulrich (Lindau, DE);
Burtscher; Peter (Nuetziders, AT);
Rheinberger; Volker (Vaduz, LI);
Durr; Heinz (Saarbrucken, DE)
|
Assignee:
|
Ivoclar AG (LI)
|
Appl. No.:
|
648810 |
Filed:
|
May 16, 1996 |
Foreign Application Priority Data
| May 26, 1995[DE] | 19520016.0 |
Current U.S. Class: |
106/35; 433/228.1; 501/13; 523/116; 523/118 |
Intern'l Class: |
A61K 006/02; C09K 009/00; C09B 057/00; C07D 471/04 |
Field of Search: |
106/35
501/13
523/116,118
433/278.1
|
References Cited
U.S. Patent Documents
3208860 | Sep., 1965 | Amistead et al. | 501/13.
|
4046781 | Sep., 1977 | Yu | 260/347.
|
4600389 | Jul., 1986 | Schwartz | 106/35.
|
4891336 | Jan., 1990 | Prassas | 501/13.
|
4979976 | Dec., 1990 | Havens et al. | 501/13.
|
5162130 | Nov., 1992 | McLaughlin | 433/203.
|
Foreign Patent Documents |
0 389 239 | Sep., 1990 | EP.
| |
0 422 514 A1 | Apr., 1991 | EP.
| |
29 06 193 C2 | Aug., 1980 | DE.
| |
30 36 103 C2 | Jul., 1981 | DE.
| |
32 47 800 C2 | Jul., 1983 | DE.
| |
32 20 257 C2 | Dec., 1983 | DE.
| |
37 17 762 C2 | Mar., 1987 | DE.
| |
39 39 998 A1 | Jun., 1991 | DE.
| |
40 29 230 A1 | Mar., 1992 | DE.
| |
41 10 611 A1 | May., 1992 | DE.
| |
2 190 917 | Dec., 1987 | GB.
| |
2 230 271 | Oct., 1990 | GB.
| |
Other References
Trotter, "Photochrome und photosensitive Guaser," Spektrum der
Wissenschaft, Jun. 1991.
Durr, "Perspektiven auf dem Gebiet der Photochromie: 1,5-Elektrocycliserung
von heteroanalogen Pentadienty-Anionen als Basis eines neuartigen
Systems," Angew. Chem., 101:427-445 (1989).
|
Primary Examiner: Bonner; Melissa
Attorney, Agent or Firm: Nixon, Hargrave, Devans & Doyle
Claims
We claim:
1. Dental material, characterized in that it contains a photochromic dye.
2. Dental material according to claim 1, characterized in that it contains,
as photochromic dye, at least one photochromic spiro› 1,8a-indolizine!
derivative.
3. Dental material according to claim 2, characterized in that it contains
at least one spiro›1,8a-dihydroindolizine! and/or
spiro›1,8a-tetrahydroindolizine! derivative.
4. Dental material according to claim 3, characterized in that it contains
at least one spiro›fluorene-9,1'›1,8a!-dihydroindolizine! derivative.
5. Dental material according to claim 4, characterized in that it contains
at least one spiro›fluorene-9,1'›1,8a!-dihydroindolizine! derivative
according to the formula
##STR4##
in which X is C--R.sup.5 or N;
R.sup.1 is H or CH.sub.3 ;
R.sup.2 is H, CH.sub.2 .dbd.C(CH.sub.3)--COO-- or, together with R.sup.3, a
fused benzene ring (--(CH.sub.2 .dbd.CH.sub.2 --).sub.2);
R.sup.3 is H, CH.sub.3, COOCH.sub.3, CN, CH.sub.2 .dbd.C(CH.sub.3)--COO--
or, together with R.sup.2, a fused benzene ring (--(CH.sub.2 .dbd.CH.sub.2
--).sub.2);
R.sup.4 is H or CH.sub.3 ;
R.sup.5 is H or CH.sub.2 .dbd.C(CH.sub.3)--COO--;
R.sup.6 is COOCH.sub.3 or COCH.sub.3 and
R.sup.7 is COOCH.sub.3 or COCH.sub.3.
6. Dental material according to claim 1, characterized in that it
additionally contains an ethylenically unsaturated monomer, a catalyst for
the hot, cold and/or photopolymerization and 20 to 90% by wt. of an
inorganic filler.
7. Dental material, characterized in that it contains a photochromic glass
which comprises the components
______________________________________
SiO.sub.2 48.0-60.0 % by wt.
Al.sub.2 O.sub.3
5.0-12.0 % by wt.
B.sub.2 O.sub.3
16.0-25.0 % by wt.
Li.sub.2 O 1.6-3.5 % by wt.
Na.sub.2 O 3.0-7.0 % by wt.
K.sub.2 O 5.0-10.0 % by wt.
TiO.sub.2 1.8-2.2 % by wt.
ZrO.sub.2 4.0-6.0 % by wt.
Ag 0.15-0.5 % by wt.
CuO 0.005-0.02 % by wt.
Cl 0.15-0.25 % by wt.
Br 0.05-0.15 % by wt.
______________________________________
8. Dental material according to claim 7, wherein the dental material is
selected from the group consisting of composite filling materials,
securing plastics for inlays, onlays, crowns and bridges and block out
materials.
9. Dental material according to claim 7, characterized in that it
additionally contains an ethylenically unsaturated monomer, a catalyst for
the hot, cold and/or photopolymerization and 20 to 90% by wt. of an
inorganic filler.
10. Dental material comprising a polymerizable material and a photochromic
material.
11. Dental material according to claim 10, wherein the photochromic
material is selected from the group consisting of a photochromic glass, a
photochromic ceramic, a photochromic glass ceramic, and combinations
thereof.
12. Dental material according to claim 10, wherein the dental material is
selected from the group consisting of composite filling materials,
securing plastics for inlays, onlays, crowns and bridges and block out
materials.
13. Dental material according to claim 10, wherein the polymerizable
material is an ethylenically unsaturated monomer and wherein said dental
material further comprises a catalyst for the hot, cold and/or
photopolymerization and 20 to 90% by wt. of an inorganic filler.
14. Dental material according to claim 1, wherein the dental material is
selected from the group consisting of composite filling materials,
securing plastics for inlays, onlays, crowns and bridges and block out
materials.
Description
The invention relates to dental materials which contain a photochromic
material such as for example a photochromic dye, a photochromic glass, a
photochromic ceramic and/or a photochromic glass ceramic and which can be
visually distinguished from the natural tooth material following
irradiation with light.
In restorative dentistry, tooth-coloured restoration materials are being
used to an increasing extent on aesthetic grounds. These materials have
the disadvantage that they can be visually distinguished from the natural
tooth substance only with difficulty, with the result that the removal of
excess material and the working and fitting of, for example, fillings
becomes more difficult. This results in healthy tooth substance frequently
being removed unnecessarily or, on the other hand, surplus dental material
being missed which then, as a retention niche, can encourage the formation
of plaque and lead to parodontal problems. Also, when tooth-coloured
fillings are being removed, the poor visibility of the transition from
filling to tooth substance frequently causes either too much healthy tooth
substance to be removed or remains of filling to be overlooked.
Similar problems arise when tooth-coloured fixing materials are used for
cementing tooth-coloured restorations.
U.S. Pat. No. 5,162,130 discloses dental materials which contain a
photosensitive material. These dental materials permit the production of
dental restorations which can be matched in terms of colour to their
environment by irradiation with UV light and subsequent heating. Since the
colour of the restorations is permanently changed by the irradiation and
heating, the photosensitive materials are not suitable for the temporary
visualization of colourless or tooth-coloured dental materials.
Dental materials are known from U.S. Pat. No. 4,600,389 which contain
fluorescent lanthanide compounds which display a reddish or greenish
fluorescence when irradiated with a mercury-vapour lamp and thus permit a
differentiation between dental material and tooth substance.
GB 2 190 917 discloses a coloured or fluorescent coating material for teeth
which forms a removable protective film.
DE 39 39 998 A1 relates to a process for the optical differentiation
between dental material and natural tooth material which is based on the
use of a fluorescent substance and special light filters.
GB 2 230 271 A discloses a dental material which contains a dye which can
be excited to fluorescence by visible light.
Fluorescent dental materials have the disadvantage that the florescence
only occurs upon simultaneous irradiation with a suitable light source, so
that, alongside the dentist's usual tools, a light guide must also be
accommodated in the oral cavity, as a result of which the dentist's work
in the narrow oral cavity is made more difficult. The use of special lamps
is also frequently necessary. Moreover, the natural tooth substance has a
strong fluorescence of its own, so that relatively high concentrations of
the fluorescent dye are needed in the dental material in order to ensure a
good distinguishability of dental material and tooth substance. This
results in a clearly visible change in colour of the dental material,
caused by the fluorescent dye, particularly in the case of fluorescent
dyes having an absorption maximum above 400 nm.
It is the object of the present invention to provide a dental material, the
colour of which can be altered by short-time irradiation with a suitable
light source in such a way that a problem-free visual differentiation of
the dental material from the natural tooth substance is ensured, and which
assumes its original colour again after a period of time sufficient to
remove surplus dental material or to work the dental material.
This object is achieved by dental materials which additionally contain a
photochromic material, such as for example a photochromic dye, a
photochromic glass, a photochromic ceramic and/or a photochromic glass
ceramic.
Photochromism is understood to be a reversible transition of a chemical
substance between two states with different absorption spectra, the
transition being caused at least in one direction by electromagnetic
radiation.
##STR1##
When irradiated with light in the wavelength range of the absorption
maximum .lambda.1 of the starting state A, the substance changes to the
higher-energy intensively coloured form B. The reverse reaction from B to
A proceeds in most cases spontaneously and, compared with the forward
reaction, at a slower speed.
Preferred photochromic materials are photochromic dyes and photochromic
glasses as well as photochromic ceramics or glass ceramics.
Suitable photochromic dyes are described for example in
Photochromism--Molecules and Systems (Durr, H.; Bouas-Laurent, H.,
Publisher, Elsevier, 1990). Preferred photochromic dye systems are based
on the cis/trans isomerism of azobenzene compounds or stilbenes, on the
interconversion or electrocyclic ring-closure/ring-opening reaction of
spiropyran systems or spirooxazins to merocyanins, or on the
1,5-electrocyclization of pentadienyl anions.
A preferred group of photochromic dyes are spiro›1,8a-indolizine!
derivatives, in particular spiro›1,8a-dihydroindolizine!- and
spiro›1,8a-tetrahydroindolizine! derivatives. Suitable derivatives and
processes for their production are disclosed for example in DE 29 06 193
C2 and DE 32 20 257 C2.
Systems which are based on a 1,5-electrocyclization, as described by H.
Durr in Angew. Chem. 101 (1989), pages 427 to 445 in Chapter 3, are
particularly preferred.
Quite particularly preferred are spiro›fluorene-9,1'›1,8a !
dihydroindolizine! derivatives, in particular derivatives according to the
formula
##STR2##
in which X is C--R.sup.5 or N;
R.sup.1 is H or CH.sub.3 ;
R.sup.2 is H, CH.sub.2 .dbd.C(CH.sub.3)--COO-- or, together with R.sup.3, a
fused benzene ring (--(CH.sub.2 .dbd.CH.sub.2 --).sub.2);
R.sup.3 is H, CH.sub.3, COOCH.sub.3, CN, CH.sub.2 .dbd.C(CH.sub.3)--COO--
or, together with R.sup.2, a fused benzene ring (--(CH.sub.2 .dbd.CH.sub.2
--).sub.2);
R.sup.4 is H or CH.sub.3 ;
R.sup.5 is H or CH.sub.2 .dbd.C(CH.sub.3)--COO--;
R.sup.6 is COOCH.sub.3 or COCH.sub.3 and
R.sup.7 is COOCH.sub.3 or COCH.sub.3.
Preferred substituents are X=N; R.sup.1 =H; R.sup.2 =H; R.sup.3 =H; R.sup.4
=H or CH.sub.3 ; R.sup.6 =COOCH.sub.3 ; R.sup.7 =COOCH.sub.3.
Quite particularly preferred systems are X=N, R.sup.1 =R.sup.2 =R.sup.3 =H;
R.sup.4 =CH.sub.3 ; R.sup.6 =R.sup.7 =COOCH.sub.3
(1'-H-2',3'-dicarbomethoxy-5'methyl-spiro›fluorene-9,1'-pyrrolo-›1,2-B!-py
ridazine!); X=N, R.sup.1 =R.sup.2 =R.sup.3 =R.sup.4 =H; R.sup.6 =R.sup.7
=COOCH.sub.3 ; X=N, R.sup.1 =CH.sub.3, R.sup.2 =R.sup.3 =H, R.sup.4
=CH.sub.3 ; R.sup.6 =R.sup.7 =COOCH.sub.3 ; and X=N, R.sup.1 =R.sup.2
=R.sup.3 =R.sup.4 =H; R.sup.6 =COCH.sub.3, R.sup.7 =COOCH.sub.3.
The change in colour of the dyes preferred according to the invention is to
be attributed to the betaine II (state B) which forms upon irradiation:
##STR3##
Photochromic dyes are preferably used in a quantity of 0.0001 to 0.1% by
wt., particularly preferably 0.002 to 0.01% by wt., relative to the total
weight of dental material. Preferred according to the invention are those
dyes whose absorption maximum .lambda.1 of the state A lies in the
wavelength range of standard commercial polymerization lamps for dental
composites, preferably in the range from 400 to 500 nm. The absorption
maximum .lambda.2 of the activated state B lies in the visible wavelength
range, so that the dental material appears coloured after irradiation and
can easily be visually distinguished from the natural tooth substance.
For the production of photo-hardenable dental materials, those dyes are
also preferred which require an irradiation time for producing the
coloured state B which is less than the time required for triggering
polymerization, so that the dental material can be coloured by a short
irradiation and surplus material can be removed in the still unhardened
but coloured state. Photochromic materials which require a radiation time
of at most 1 to 3 seconds for producing the coloured state B are thus
particularly preferred.
For the initial hardening, the dental material is irradiated again, e.g.
for 10 seconds, the hardened material remaining coloured and thus readily
recognizable. The dental material is then coloured; for the final
hardening, it is again decolorized. In principle, however, it is also
possible to harden the dental material immediately by a single longer
irradiation.
Self-hardening dental materials usually require several minutes to harden,
normally about 2 to 4 minutes. Here, too, photochromic materials which
require an irradiation time of at most 1 to 3 seconds to produce the
coloured state are preferred, so that surplus material can be removed in
the unhardened state.
The photochromic dyes according to the invention are suitable for producing
both reversible and irreversible decolorizable dental materials.
Irreversibly decolorizable dental materials are suitable in particular for
cementing tooth-coloured ceramic restorations (for example inlays, onlays
and crowns). Here, it is frequently desired that the photochromic cement
used for the cementing changes colour only during the cementation, but is
permanently colourless or tooth-coloured following cementation, in order
to avoid the cement changing colour for example by insolation,
particularly in the front teeth region.
The aforementioned spiro›1,8a-indolizine! derivatives are particularly
suitable for producing irreversibly decolorizable dental materials, since
they are frequently destroyed during radical polymerization of the dental
material, which results in a non-reversible decolorization. This property
also permits a selective decolorization of the dental material after the
dental restoration is finished.
Since, in the case of irreversibly decolorizable dental materials,
hardening of the material is associated with a partial decolorization of
the material because the photochromic dye is destroyed, hardening in two
stages is recommended in these cases.
After the first short-term irradiation of the dental material to produce
the coloured state and optionally after removing or working the unhardened
dental material, it is irradiated a second time for superficial hardening.
In most cases, an irradiation time of about 10 seconds is sufficient for
this purpose. If necessary, the hardened but still coloured dental
material surpluses can then be removed. The dental material is then
completely hardened by a relatively .long irradiation of preferably 40 to
60 seconds, considerable decolorization taking place.
Complete decolorization of the material takes place by the subsequent
reverse reaction of non-destroyed dye molecules to the starting state A
and, if necessary, by removing the surface layer of the material. In the
surface layer, radical polymerization is frequently inhibited by oxygen
which diffuses in, so that polymerization and thus destruction of the
photochromic dye is incomplete in this layer. In practice, this layer,
which is usually about 100 .mu.m thick, is removed upon polishing of the
fillings and cement edges.
The time taken for complete decolorization of the material depends on the
type and the quantity of dye used. In the case of the dyes preferred
according to the invention, the material is already completely decolorized
during the 40-60 second irradiation in the case of a dye content of about
0.002% by wt., whilst for a dye content of about 0.01% by wt. complete
decolorization takes place within 24 hours with the exclusion of light
after irradiation for 40 to 60 seconds.
Permanently reversible photochromic dental materials are obtained with the
combination of organic photochromic dyes with heat-hardening composites
when the dental material is hardened in the uncolored state. In the case
of the photochromic dyes preferred according to the invention, whose
photochromism is based on a 1,5-electrocyclization, this is presumably to
be attributed to the fact that the dyes are accessible only in the
open-chained coloured form to the radical destruction. Heat-hardening
dental materials are suitable particularly for producing inlays and
onlays.
Permanently reversible photochromic dental materials based on organic
photochromic dyes can also be produced with self- or cold-hardening and
dual-hardenable systems. In the case of a self- or cold-hardening system,
an amine-containing base paste is mixed with a peroxide-containing
catalyst paste. The radical polymerization is initiated by the reaction of
amine and peroxide. Dibenzoyl peroxide is the preferred catalyst.
In the case of dual-hardenable systems, the base paste additionally
contains a photoinitiator, such as for example camphor quinone, so that
the base paste can be used either on its own as a light-hardening dental
material or together with the catalyst paste as a light- and
self-hardening dental material.
In the case of self- and dual-hardening systems, the reversibility of the
colour change is dependent on the ratio of catalyst to photochromic dye.
When using the preferred catalyst dibenzoyl peroxide and a usual catalyst
concentration of for example about 0.75% by wt. dibenzoyl peroxide (50%),
a dye concentration of 0.01 to 0.1% by wt. is preferred. Even in the case
of self- and dual-hardening systems, reversible photochromism is only
achieved when hardening of the dental material takes place in the
uncoloured state.
In the case of the preferred photochromic dyes, the decolorizing time for
reversibly photochromic dental materials both in the case of heat- and
also of self- and dual-hardening systems is about 2 hours, preferably
about 1 hour. However, since the working of the dental material and
removal of surplus dental material usually takes place in the light of an
operating lamp (wavelength range about 400-700 nm), no decolorization
normally takes place during working, so that photochromic materials with a
clearly lower decolorization time are also suitable according to the
invention.
Photochromic glasses suitable according to the invention are for example
disclosed in U.S. Pat. No. 4,891,336, U.S. Pat. No. 4,979,976 and EP 0 422
514 A1. These are photochromic glasses based on metal halides.
Silicon-aluminium-borate glasses, whose photochromic effect is based on
the interaction of silver, chlorine, bromine and copper, in each case in
several different oxidation stages, are particularly suitable.
Particularly preferred glasses are described in DE 30 36 103 C 2, U.S.
Pat. No. 3,208,860 and in U.S. Pat. No. 4,046,781. Quite particularly
preferred are glasses with the composition:
______________________________________
Constituent % by wt.
______________________________________
SiO.sub.2 48.0-60.0
Al.sub.2 O.sub.3
5.0-12.0
B.sub.2 O.sub.3
16.0-25.0
Li.sub.2 O 1.6-3.5
Na.sub.2 O 3.0-7.0
K.sub.2 O 5.0-10.0
TiO.sub.2 1.8-2.2
ZrO.sub.2 4.0-6.0
Ag 0.15-0.5
CuO 0.005-0.02
Cl 0.15-0.25
Br 0.05-0.15
______________________________________
Such glasses are for example marketed by Deutsche Spezialglas AG under the
name "Photosolar Supergrey D-1426".
Dental materials based on metal halide-containing glasses, ceramics or
glass ceramics turn dark when irradiated with light. In general, they
react sensitively to the whole spectrum of visible light, without showing
a particularly marked absorption maximum. An irradiation time of 20 to 40
seconds is generally sufficient to make the dental material clearly
visible.
The colour of the photochromic glasses on exposure to light is based on the
reduction of ionic silver (state A) to elementary silver (state B), which
is again oxidized under the exclusion of light with simultaneous
decolorization. Complete decolorization preferably takes place within 0.5
to 1.5 hours.
As a rule, dental materials based on photochromic glasses, ceramics or
glass ceramics display a permanent reversibility of the photochromism, and
they do not lose their ability for photochromism even when the dental
material containing them, such as for example a filling material, is
subjected over a relatively long period of time to the chemical and
physical influences which affect natural teeth. On aesthetic grounds these
materials are therefore preferably suitable for use in the side tooth
region or as underfilling materials.
Photochromic glasses, ceramics and/or glass ceramics are preferably used as
fillers, preferably in a concentration of 10 to 90% by wt., particularly
preferably 30 to 60% by wt. relative to the total weight of the dental
material. Glasses in powder form having an average grain size of 0.7 to 20
.mu.m, in particular 0.7 to 5 .mu.m and glasses with a refractive index of
1.50 to 1.58 are preferred for use in dental materials. The choice of
polymerization catalyst does not have an effect on the photochromism of
the glasses, ceramics and glass ceramics.
The photochromic materials according to the invention are compatible with
very different dental materials and prove advantageous particularly when
incorporated into colourless or tooth-coloured dental materials, since
they essentially lead to no visible change in the colour of the material.
Dental materials within the meaning of the invention are in particular
composite filling materials, securing plastics for inlays, onlays, crowns
and bridges and block-out materials.
Dental materials based on a polymerizable, ethylenically unsaturated
monomer as binding agent, a catalyst for the hot, cold and/or
photopolymerization and 20 to 90% by wt. of an inorganic filler are
preferred.
Suitable as polymerizable organic binding agents are all binding agents
which can be used for a dental material, in particular monofunctional or
polyfunctional methacrylates which can be used alone or in mixtures.
Coming into consideration as examples of these compounds are methyl
methacrylate, isobutyl methacrylate, cyclohexyl methacrylate,
tetraethylene glycol dimethacrylate, triethylene glycol dimethacrylate,
diethylene glycol dimethacrylate, ethylene glycol dimethacrylate,
polyethylene glycol dimethacrylate, butanediol dimethacrylate, hexanediol
dimethacrylate, decanediol dimethacrylate, dodecanediol dimethacrylate,
bisphenol-A dimethacrylate, trimethylolpropane trimethacrylate,
2,2-bis-4-(3-methacryloxy-2-hydroxy-propoxy)-phenyl propane (bis-GMA) and
the reaction products of isocyanates, in particular di- and/or
triisocyanates and OH group-containing methacrylates. Examples of these
are the reaction products of 1 mol hexamethylene diisocyanate with 2 mol
2-hydroxyethylene methacrylate, of 1 mol tri-(6-isocyanatohexyl) biuret
with 3 mol 2-hydroxyethyl methacrylate and (6-isocyanatohexyl) biuret with
3 mol 2-hydroxyethyl methacrylate and of 1 mol 2,2,4-trimethyl
hexamethylene diisocyanate with 2 mol 2-hydroxyethyl methacrylate.
Preferred as catalysts for the heat-hardening systems are peroxides, in
particular dibenzoyl peroxide, dilauroyl peroxide, tert.-butyl peroctate
and tert.-butyl perbenzoate. 2,2'-azoisobutyric acid nitrile (AIBN),
benzpinacol and 2,2'-dialkyl benzpinacols are also suitable.
Used as catalysts for the cold polymerization are radical-supplying
systems, for example benzoyl or lauroyl peroxide together with amines such
as N,N-dimethyl-p-toluidine, N,N-dihydroxyethyl-p-toluidine or other
structurally related amines.
Usable as initiators for the photopolymerization are for example
benzophenone and its derivatives and benzoin and its derivatives. Other
preferred photoinitiators are the .alpha.-diketones such as
9,10-phenanthrene quinone, diacetyl, furil, anisil, 4,4'-dichlorobenzil
and 4,4'-dialkoxy benzil. Camphor quinone is particularly preferably used.
Combinations of cold and photocatalysts are suitable as catalysts for
dual-hardenable systems. The use of camphor quinone and dibenzoyl peroxide
in combination with the aforementioned amines is preferred.
Used as inorganic fillers are e.g. quartz, glass ceramic or glass powders,
the oxides of aluminium or silicon, barium silicate glasses and Li/Al
silicate glasses, barium glasses, very finely divided silicas, in
particular pyrogenic or precipitated silicas.
Suitable fillers are for example disclosed in DE-OS 40 29 230. Fillers of
type (A) are described in DE-PS 32 47 800.
The photochromic glasses according to the invention are preferably used as
component (B), either alone or in combination with a barium silicate glass
which has the required parameters.
The invention is described in more detail below with reference to examples.
EXAMPLE 1
Photochromic, Light-Hardening Tooth-Coloured Composite Cement
A base paste having the following composition is produced by mixing the
components (analogous to DE 40 29 230 A1):
______________________________________
Component % by wt.
______________________________________
Ba--Al silicate glass, silanized
40.0
Ytterbium trifluoride 25.0
Spheroidal mixed oxide, silanized*
10.0
Bisphenol-A glycidyl dimethacrylate (bis-GMA)
12.28
Triethylene glycol dimethacrylate (TEGDMA)
6.22
Urethane dimethacrylate (UDMA)**
6.22
Camphor quinone 0.07
Cyanoethyl methylaniline 0.07
N,N-diethyl-3,5-di-tert.-butylaniline
0.1
3,5-di-tert.-butyl-4-hydroxytoluene (BHT)
0.03
HD 579 0.01
______________________________________
*Filler A according to DE 40 29 230 A1
**Reaction product of 1 mol trimethylhexamethylene diisocyanate and 2 mol
hydroxyethyl methacrylate
N,N-diethyl-3,5-di-tert.-butylaniline, BHT and, as fillers, silanized
Ba-Al-silicate glass, ytterbium trifluoride and spheroidal mixed oxide are
incorporated into a monomer mixture of bis-GMA, TEGDMA, UDMA, camphor
quinone and cyanoethyl methylaniline. 0.01% by wt. of the photochromic dye
HD 579 (Table 1) are also added.
A catalyst paste having the following composition is also produced
(analogous to DE 40 29 230 A1):
______________________________________
Component % by wt.
______________________________________
Ba--Al silicate glass, silanized
40.0
Ytterbium trifluoride
25.0
Spheroidal mixed oxide, silanized
10.0
Bis-GMA 12.22
TEGDMA 6.0
UDMA 6.0
Benzoyl peroxide (50%)
0.75
BHT 0.03
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Into a monomer mixture of bis-GMA, TEGDMA, UDMA, BHT and 50% benzoyl
peroxide are incorporated, as fillers, silanized Ba-Al silicate glass,
ytterbium trifluoride and spheroidal mixed oxide.
The pastes are mixed in the ratio 1:1 and inserted with the part to be
cemented (crown, bridge, veneer, inlay, onlay). The cement emerging from
the cementing crevice is irradiated for 1 to 3 seconds with a standard
commercial polymerization lamp (Heliolux.RTM. GTE, Vivadent) at a
wavelength of 400 to 500 nm. The cement suddenly turns an intense red, but
remains thinly viscous. In this phase the coarsest surpluses can easily be
removed.
After irradiating further for about 20 seconds, the cement polymerizes to a
hard material which is also red in colour. The polymerized-out surpluses
remain easily visible and can be removed with precision.
By irradiating for a further 40 to 60 seconds the cement is almost
completely decolorized. The remaining slight pink colour disappears after
storage without irradiation within 24 hours. The hardened material has a
tooth-coloured appearance. The decolorization is irreversible since the
dye used is destroyed by the radical polymerization.
EXAMPLES 2 to 10
A base paste is produced according to Example 1, but using the dyes given
in Table 1 as photochromic materials. The base pastes are mixed with the
catalyst paste according to Example 1 and irradiated as described in
Example 1. The dental materials display different colours (Table 1) and
colour intensities, depending on the dye chosen. Decolorization is
irreversible in all cases.
EXAMPLE 11
Photochromic Filling Material
A material having the following composition is produced by mixing the
components:
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Components % by wt.
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Photosolar supergrey D-1426*
15.0
Ba--Al silicate glass, silanized
35.0
Ytterbium trifluoride 15.0
Spheroidal mixed oxide, silanized
15.0
Aerosil OX-50,** silanized
1.0
Bis-GMA 8.0
TEGDMA 3.8
UDMA 7.02
Monomethyl hydroquinone (MeHQ)
0.02
Camphor quinone 0.06
Cyanoethyl methylaniline
0.1
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*Photochromic glass from Deutsche Spezial Glas AG, the glass is ground to
an average grain size of 0.7 to 5 .mu.m
**Aerosil OX50 (Degussa AG)
The material is introduced into a cavity like a usual filling material and
irradiated for 40 to 60 seconds with a polymerization lamp (Heliolux GTE,
Vivadent) with a wavelength of 400 to 500 nm. Upon irradiating the paste,
the composite hardens and immediately turns grey. Within 1.5 hours'
storage with the exclusion of light, the testpiece has again lost its
colour and has a tooth-coloured appearance. When the testpiece is
irradiated again (about 10 seconds), it once again turns grey and, after
storage with the exclusion of light, decolorization again takes place.
This process can be repeated as often as desired.
TABLE 1
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Derivatives of compound I
Ex-
am- Col-
ple
Dye X R.sup.1
R.sup.2 R.sup.3 R.sup.4
R.sup.5 R.sup.6
R.sup.7
our
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1 HD 579
N H H H CH.sub.3
-- COOCH.sub.3
COOCH.sub.3
red
2 HD 578
N H H H H -- COOCH.sub.3
COOCH.sub.3
red
3 HD 580
N H COOCH.sub.3 H H -- COOCH.sub.3
COOCH.sub.3
red
4 HD 581
N H H CN H -- COOCH.sub.3
COOCH.sub.3
red
5 HD 582
N CH.sub.3
H H CH.sub.3
-- COOCH.sub.3
COOCH.sub.3
green
6 HD 604
N H --(CH.sub.2 .tbd.CH.sub.2).sub.2 --
H -- COCH.sub.3
COCH.sub.3
blue-
violet
7 HD 606
N H H H H -- COCH.sub.3
COOCH.sub.3
red
8 HD 607
C-R.sup.5
H CH.sub.2 .tbd.C--(CH.sub.3)--COO--
H H H COOCH.sub.3
COOCH.sub.3
green
9 HD 608
C-R.sup.5
H H H H CH.sub.2 .dbd.C(CH.sub.3)--COO--
COOCH.sub.3
COOCH.sub.3
green
10 HD 609
C-R.sup.5
H H CH.sub.2 .dbd.C(CH.sub.3)--COO--
H H COOCH.sub.3
COOCH.sub.3
green
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